7. _On the Composition of Cyanic Acid_.—M. Wohler some time since announced the production of cyanic acid, and cyanates, corresponding in composition to the substance presumed to exist in the fulminating compounds of silver, mercury, &c., the nature of which was made out by MM. Liebig and Gay Lussac. M. Liebig, upon repeating M. Wohler’s experiments upon his cyanate of silver, obtained only 71.012 per cent. of oxide of silver, instead of 77.23, which was the quantity present according to M. Wohler’s analysis, and concluded that the acid was the cyanous, and not the cyanic. The latter philosopher was consequently induced to repeat his experiments: one of his methods of decomposing the cyanate of silver was by muriatic acid gas: at first liquid cyanic acid forms, which is very soon transformed into a white crystalline mass; but, on continuing the operation, and applying a higher heat, a large quantity of muriate of ammonia and cyanic acid is evolved. This process indicated 77.5 per cent. of oxide of silver in the salt. Another process consisted in dissolving the cyanate in nitric acid, and precipitating the silver by muriatic acid, the result was 77.05 of oxide per cent. A third analysis, made by reducing the silver of the salt, gave a result of 77.35 per cent. oxide. The mean of these is 77.3, and the theoretical number obtained by calculation is 77.23, so that the acid appears to be truly the cyanic; and the curious fact of its being the same in composition with that in the fulminating compounds of silver and mercury, but very unlike in properties, still remains undisturbed.—_Bull. Univ._, A. viii. 53. 8. _Iodous Acid_.—According to M. Wohler, the iodous acid of [p204] M. Sementini[35] is nothing more than a mixture of chloride of iodine and iodine. When saturated with carbonate of soda, the iodine in solution is precipitated, and on evaporating the solution to dryness, and heating it strongly, the residue fuses, and by proper tests is found to be a mixture of chloride and iodide of sodium. These statements apply only to the iodous acid: as to the oxide of iodine, no source of chlorine exists in the process last described by M. Sementini. FOOTNOTE: [35] See the last volume of this Journal, p. 477. 9. _On Manganesic Acid, by_ M. Unverdorben.—When manganesate of potash is distilled with a little anhydrous sulphuric acid, manganesic acid is evolved in the form of a red transparent gas, which dissolves in water, forming a red solution. The gas frequently decomposes spontaneously in the retort, with explosion, producing oxide of manganese and oxygen. Manganesate of potash was analysed by distilling it with excess of sulphuric acid, collecting the oxygen disengaged, and estimating the proportion of protoxide of manganese and salts of potash remaining in the retort. According to these experiments the acid consists of Manganese 58.74 Oxygen 41.26 ------ 100.00